Determination of the effective charge of different nanocolloids at high ionic strength using conductivity and acoustophoresis

We developed a theoretical approach to describe the resulting signal without neglecting the signal from the nanocolloid (conductivity) or from the salt (acoustophoresis). We applied this approach to experimental results of conductivity and ultrasonic vibration potential (UVP) for: (i) spherical nanomagnetic colloids (Ri = 5 nm) and (ii) plate-like colloids (laponite). As the sizes are known from other techniques, we deduced in a coherent way the effective charges of the particles, which permit to reproduce conductivity and acoustophoresis experiments simultaneously. The variation of the charge of the magnetic nanocolloids shows an unusual behavior when decreasing the volume fraction.